Olefins, especially those in the 6-22 carbon number range, are useful chemical building blocks, for example, for making surfactant products. They can readily be converted to sulfonic acids by reaction with SO.sub.3 or mixtures of SO.sub.2 and oxygen. The alkali metal salts of the olefin sulfonic acids are very useful in detergents. U.S. Pat. No. 3,424,693 discloses the sulfonation of .alpha.-olefins followed by alkaline neutralization to form a useful surfactant. A similar process is disclosed in U.S. Pat. No. 3,860,528. Useful organic sulfonate surfactants can also be made by oxidizing an aliphatic hydrocarbyl mercaptan. Oxidation of alkyl mercaptan by reaction with oxygen in the presence of catalytic amounts of nitrogen oxide is disclosed in U.S. Pat. No. 2,505,910. Oxidation of sec-alkyl mercaptan with nitric acid to form sec-alkyl sulfonic acid which can be neutralized to form a surfactant is discussed in U.S. Pat. No. 2,187,335; U.S. Pat. No. 2,187,338 and U.S. Pat. No. 2,187,339.
The reaction of olefins with hydrogen sulfide to form mercaptan is known. U.S. Pat. No. 2,434,510; U.S. Pat. No. 2,443,852 and U.S. Pat. No. 2,468,739 disclose the reaction of olefins such as triisobutylene with hydrogen sulfide in the presence of an acid or metal halide catalyst to form sec/or tert-alkyl mercaptan. U.S. Pat. No. 3,050,452 discloses the reaction of olefins with hydrogen sulfide in the presence of a trialkyl phosphite using ultraviolet light as a catalyst.
Several commercial processes are available for producing olefins in the detergent range. Such olefins can be made by the thermal cracking of wax paraffins. They can also be made by catalyzed ethylene oligomerization or via chain growth on aluminum using Ziegler chemistry. The latter process involves the reaction of ethylene with triethylaluminum to form higher trialkylaluminum and the displacement of the alkyl groups from the aluminum to form olefin mixtures. These olefin mixtures are mainly linear .alpha.-olefins but contain lesser amounts of internal olefins and vinylidene olefins, the latter being 1,1-disubstituted ethylenes. In some cases it is desirable to remove the vinylidene olefins to obtain a mixture of linear .alpha.-olefins containing minor amounts of internal olefins to meet certain specific applications requirements. Since the vinylidene olefins boil in the same range as the linear .alpha.-olefins and internal olefins, they cannot be readily separated by distillation. Thus a need exists for a method of selectively separating vinylidene olefins from mixtures of olefins containing both vinylidene olefins and non-vinylidene olefins.